Over the past several years, the automotive industry has shifted to the use of electronically controlled fuel injection systems to the point where practically all new passenger cars manufactured in the United States today are equipped with electronic fuel injection systems. However, there are many older vehicles still on the road equipped with conventional carburetors, and a certain number of new vehicles manufactured in foreign countries continue to employ carburetors as original equipment. The phasing out of carburetors as original equipment by the automotive industry in the United States and by many foreign automobile manufacturers presents a major economic problem both to original equipment carburetor manufacturers and suppliers and to owners of carburetor equipped vehicles. The substantially reduced and still declining market for carburetors makes it uneconomical for the manufacturer to maintain high volume production lines and the consequent price increases must be passed on to the purchaser. The problem is aggravated because of the fact that carburetors typically are designed for a specific model of engine and thus there is a wide variety of existing models of carburetors which are not interchangeable with each other. Automotive part supply houses can no longer afford to maintain complete replacement carburetor inventories.
The prior art has proposed the use of so-called stand alone (self contained) fuel injection systems designed to be able, among other things, to constitute a retro-fit replacement for a wide variety of carburetors and which, in some instances, may include an electronic control unit provided with externally accessible adjustments which enable the system to be tuned for use with automotive engines whose displacement may differ over a wide range.
The invention as herein disclosed is primarily intended to enhance the operation of such fuel injection systems, and in particular the retro-fit type of injection system, by providing control or output means, which are responsive to indicia of engine operating conditions and operating parameters, whereby the metering function of the injection system is made to closely follow the actual demands by the engine for fuel.